Bowling ball with epoxy resin cover



Sept. 28, 1965 F. G. FIRTH ETAL 3,208,750 BOWLING BALL WITH EPOXY RESIN COVER Q Filed March 14, 1960 2 She ets-Sheet 1 H1 '73 f F jZm/cv; 65066.: I727 24 DAV/0M 614, 49

- JNVENTORJ'.

g I M I Sept. 28, 1965 F. a. FIRTH ETAL BOWLING BALL WITH EPOXY RESIN COVER 2 Sheets-Sheet 2 Filed March 14, 1360 INVENTORI- ZINC/f vkcuuu puup flrroeunz 3,208,750 BOWLING BALL WITH EPOXY RESIN COVER Francis George Firth, Los Angeles, and David M. Caplan, Los Alamitos, Calif., assiguors to W. I. Voit Rubber 'Corp., a corporation of California Filed Mar. 14, 1960, Ser. No. 14,620

15 Claims. (Cl. 27363) 'balls are subject to undue wear in that they tend to chip around the finger holes, have poor abrasion resistance and quickly accumulate bits of dirt on their surface which causes pitting and scarring of the surface. Further, because of their composition these bowling balls almost always have a drab, dark color.

It is, therefore, the principal object of this'invention v United States Patent glycidyl ether of bisphenol A. Besides the reactive oxirane ring structure there can be present other reactive centers such as hydroxyl, carboxyl or other sites capable of being used in chain extension or cross-linking mechanisms and which may require other condensation agents than catalysts, anhydrides or polyfunctional amines.

to provide a bowling ball having an outside surface which I is able to withstand the shocks to which the ball is subjected in bowling games, which surface is able to with stand abrasion, is smoother than prior balls and does not chip or crack.

It is a further object of this invention to provide a bowling ball which has the ability to repel dirt and retain its smooth appearance.

A still further object of this invention is'to provide bowling balls in a variety of pleasing colors which retain their color through repeated use.

It is an additional object of this invention to provide bowling balls having inner cores that are lighter, more cushion-like and thereby provide greater resiliency and tone than found in prior bowling balls.

Other objects will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, said invention then comprises the features hereinafter fully described and particularly pointed out in the claims, the following description setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

Referring to the drawings, FIG. 1- is a vertical section or a mold, or die, and of raw material ribbon being placed into the mold.

FIG. 2 is a side view of a completely closed mold.

FIG. 3 is a side viewof a partially open mold of the type illustrated in FIG. 2.

FIG. 4 is a partially open view of an additional mold used in the course of manufacturing the ball.

FIG. 5 is a schematic diagram of a molding system using the mold illustrated in FIG. 4.

FIG. 6 is a sectional view of an additional mold used for making the wooden ball cores. 1

Broadly stated, the present invention comprises a bowling ball comprising at least one core and an epoxy resin cover contiguous with and completely enveloping said core, said epoxy resin having an epoxide equivalent weight in the range of 170 to about 400.

Bowling balls are generally of either two-part or threepart construction. In a ball of two-part construction there is a core and cover; and in a ball of three-part construction there is an inner core, an outer core surrounding and contiguous with the inner core, and a cover contiguous with the outer core and completely enveloping the same.

The bowling balls of the present invention are primarily distinguished by their outer coverings, namely, a covering Typical commercial epoxy resins of varying molecular weights are generally mixtures of polyglycidyl ethers made by the reaction of epichlorohydrin and 2,2-bis(4-hydroxyphenyl)propane in the presence of alkali. The manufacture of epoxy resins applicable to the present invention is described, for example, in US. Patents 2,324,483, 2,444,333, 2,500,600 and 2,633,458. The low molecular weight resins of 400 or less epoxide equivalent weight are liquid. We have found that epoxy resins with an epoxide equivalent weight of from about 170 to about 400, and preferably from 170 to 179, have remarkable dimensional stability during cure, and when applied to a bowling ball core material they have outstanding adhesive properties, very little shrinkage and result in a finished ball having an extremely smooth surface with accurate dimensions. These outer covers additionally accept a wide range of fillers and pigments and the finished ball has a hard surface coupled with great toughness and shock resistance.

In applying the epoxy resins to core materials to produce abowling ball, the resins are incorporated into a formulation designed for this specific end use. Commera cial formulators readily know the various additives necessary to obtain a finished or cured product having the requisite color, toughness, dimensional stability, adhesion and abrasion resistance. Although functional end-use properties are determined primarily by the resin itself, a typical formulation could include resin, curing agent (hardener), diluent, filler, resinous modifier and pigment.

The viscosity of epoxy resins can be lowered by the addition of non-reactive or standard reactive diluents. However, the ellect of diluent addition is not only the reduction of viscosity. For example, diluents aid in obtaining high filler loadings at lower final viscosity; they can reduce internal strain during cure; and they can lengthen pot life and increase impact resistance. Large excesses of diluent should be avoided, however, as they may degrade desirable physical properties. In the preferred embodiment of our invention we use from about 2 to about 20 parts of reactive diluent per parts of epoxy resin. Typical standard reactive diluents applicable to the present invention are allyl glycidyl ether, butyl glycidyl ether, phenyl glycidyl ether and styrene oxide. Each of. these diluents contains an epoxide group which reacts with the hardener, just as does the epoxy group in the resin, and thus makes the diluent an integral chemical part of the cured resin. Non-reactive diluents or solvents are to be avoided in the present formulations as they could cause excessive shrinkage if evaporated from plexes, phthalic anhydride: hexahydro phthalic anhydride, dodecenyl succinic anhydrid and pyromellitic dianhydride are typical examples of such useful curing agents.

In the preferred embodiment of our invention we use from about to about 70 parts of filler per 100 parts of resin. These fillers not only enable epoxy formulators to reduce costs, but they also contribute to such desirable properties as increased strength, impact resistance, and decreased shrinkage. Among the typical fillers useful in the present formulations are clays, asbestos fibers, glass fibers, nylon fibers, Dacron fibers, Orlon fibers, powdered glass, powdered metals, aluminum oxide, silica and mica. Asbestos short ends are especially useful in the present formulations because of low cost, ease of incorporation, improved reinforcement and the large volume which can be incorporated into the resin mix. Additionally, fillers can also be used as dyes or pigments to impart color to the final product."

Resinous modifiers or flexibilizers can be used in the resin formulations of the present invention in amounts of from 0 to about 100 parts per 100 parts of epoxy resin. These resinous modifiers or flexibilizers either in reaction with the epoxy resins or in solution with them can be used to favorably affect impact resistance, water resist ance, heat resistance and flexibility of the final cured product. Additionally, resinous modifiers based on melamine,

urea, phenolics, polyamides, propylene glycols, or poly-I ols and polysulfide rubber may act ascuring agents for the epoxy resins through reaction with the epoxide groups or the hydroxyl groups.

The purpose of pigments in the epoxy formulations is to develop a pleasing shade on the outside of the ball. A wide variety of pigments are available; they may be of inorganic or organic nature, and may be used in amounts up to 20 parts per 100 parts of epoxy resin de-, pending on the strength of the pigment used. White and pastel shades can be obtained by the use of titanium dioxide, lithopone, zinc oxide and similar other. white pigments, alone or in conjunction with iron oxides, carbon blacks, cadmium colors, cobalt colors, and similar materials used in the coloration of paints and plastics.

The following examples are typical formulations useful in producing the covered bowling balls of the present invention: Y r

The formulation of this example is composed of Dow epoxy resin 332 curedwith a typical amine hardener. Dow epoxy resin 332 is a diglycidyl ether of bisphenol A having an average epoxide equivalent weight of 179.

Dow epoxy resin 332 100. Diethylenetriamine 8-12 p.h.r. (Parts (wt.) per hundred parts of resin (wt.)). 1 II Dow epoxy resin 332 100 Boron trifiuoride monoethylamine complex p.h.r 3

, III Dow epoxy resin 332 100 Butyl glycidyl ether p.h.r 12 Calcium carbonate p.h.r 50 Asbestos fibers p.h.r 50 Versamid 115 (a polymeric epoxy curing agent made by the condensation of dimerized or trimerized oil fatty acids and ethylene diamine) p.h.r 60 Thiokol LP3 (a liquid poly sulfide rubber rubber flexibilizer prepared by the reaction of organic dihalides and sodium polysulfide) p.h.r Titanium dioxide p.h.r 6 Cadmium-selenium red pigment p.h.r 3 Diethylene triamine p.h.r- 10 As previously stated, the foregoing epoxy resin cover may be applied to a single or double core. The cores used in the present bowling balls may be hard rubber, a mixture of hard rubber and cork and wood flour, wood chips, sawdust or shavings mixed with inorganic fibers and held together with a binder, such as phenol formaldehyde, epoxy resins, polyester resins, melamine, urea form aldehyde, etc. I

Referring .to FIG. 1, a plurality of hardrubber strips 10, preheated to a temperature of approximately 140 F., is pressed into a mold 12 by means of a press 14, a sufiicient number of strips being deposited into the mold 12 so as to fill, upon compression, this mold completely, up to its upper surface 30, 'with the material used for making the core. The mold, or die, 12 is provided with a flange 16 having slots 18 and 20 for subsequent inser tion of bolts 22 and 24 illustrated in FIG. 2. These bolts are used for clamping together two molds, each (BaSO and reclaimed rubber.

containing a hemispherical core, on top of each other in the manner indicated in FIG. 2 so as to produce a complete ball core from two hemispherical cores in the course of its manufacture. 7

When it is desirable to produce hard rubber cores, then 7 a conventional and known composition of hard rubber is used for making strips 10, such composition usually in cluding in excess of 30% of sulfur and additional hard fillers, such as carbon black, hard rubber dust, barytes When such hard rubber stock is used, then ribbon 10, which may have such size as 5 inches by 16 inches by to /8 inch thick, is preheated to a temperature from 100-140' F. and mold, or die, 12 is also preheated to a'temperature in the order of 100-150 F. prior to its placing under the hydraulic ram 14. It should also be mentioned here that a high density weight block 26, or a plurality of such blocks, is placed at the bottom of. mold 12, this block being used as a means for compensating for the reduction in weight in direct vicinity of this block 26, which takes place when finger holes are subsequently drilled in the ball. The high density block 26 can also be made of hard rubber, in which case its density is increased by increasing the percentage of barytes, or other heavy filler.

The method disclosed in FIGS. 1, 2 and 3 for making the core of the ball'is also suitable for making the core of balls which contain a mixture of *hard rubber and cork. When cork is used, then the granulated cork, having various sizes from approximately to inch, is mixed with hard rubber prior to making ribbon 10. In this case, it is often possible to discard the step of making strips of ribbon 10 altogether and using the mixture of hard rubber composition and cork merely as a bulk which is deposited into mold 12 in sufficient amount for filling mold 12 to the until its flange 32 engages the upper surface 30 of mold 12. Batches of this type generally are weighed or measured in advance and then deposited into mold 12 so as to produce the desired density, pressure, and compression of the material within the mold, the above parameters determining the final weight of the finished ball.

After two hemispheres of the above type are made in 'two respective molds 12, these two molds are used in the manner illustrated in FIG. 2, with one mold acting as a base 12 and the second mold 12a acting as a cover for the second mold. The two identical molds are then tightly clamped together by means of bolts 22 and 24, or other more convenient means, and this composite mold, holding within it 'two hemispherical cores 34 and 36, is placed in any suitable heating medium, such as a steam autoclave, where it is heated from 8 to 13 hours at 245-260 F., depending on the composition of the core. The length of time for producing proper cure is a function of the amount of cork used in the raw materials; the larger the percentage of the cork used, the longer is the time of the cure. After the above period of curing time, the composite mold 12-12a is taken out of the. autoclave and is cooled for a period of from 4 to 8 hours, whereupon the mold is opened, in the manner illustrated in FIG. 3, and the cured core is then taken out of the mold. The two hemispheres 36 and 34 are fused together during the curing step and become a single sphere 38'.

The mold may have a highly polished, plated metallic surface, made of suchimetal as plated chrome, which facilitates the separation of the molded core from the mold. It-isalso customary to use mold lubricants or stripping compounds, such as silicone, for preventing any possibility of establishing a bond between the material being molded and the mold, and, in the mold of this type, the chromium-plated surface can be eliminated to reduce the original cost of the mold. The outside diameter of the cured core 38 is made slightly larger than its final diameter; for example, its outside diameter may be in the order of 7 7 down on a lathe to a 7% to 7%? size.

Referring now to FIGS. 4 and 5, which illustrate a transfer mold apparatus, a piston-cylinder combination 50-51 is. connected to an outgoing duct 52. Duct 52 is connected to an injection mold 53 including an upper and it is subsequently turned half 54 and a lower half 55 each having a hemispherical recess for receiving sphere 38, and synthetic resin which is injected or transferred into the mold53 by means of piston 50. Mold 53 is provided with cavities 56 and 57 which surround the hemispherical walls 58 and 59'of the mold. 60 and 61 of the mold are polished and then chromium plated for facilitating the removal of the molded balls. Surfaces 60 and 61 are coated with. a suitable mold lubricant before injecting the resin into the mold, such as silicone or a soapy solution, both of which prevent the formation of a bond between these surfaces and the injected resin. Mold 53' is provided with two 0 rings 62 and 63 and a cylindrical recess 64 which is located directly at the two matching surfaces 65 and 66 of the two molds 54 and 55 so that each mold has a semi-cylin-. drical recess equal to and matching the semi-cylindrical recess in the complementary mold. Accordingly, the recess is located alongand on the great circle of core 38. Mold 53 is also provided with a tapered cylindrical recess 6869 which is also located on the same great circle and diametrically opposite the location of recess 64. The recesses 68 and 69 are used for inserting a mandrel, or pin, 70'and a threaded bushing 71 which fits into recess 69. The outer end of the mandrel is also threaded 'and is provided with a suitable hexagonal or square head 72 which is used for inserting or scnewing in and out the mandrel for engaging core '38 after it has been placed into the lower half 55 of the mold. A

bore 74 is also provided at the same great circle of core The inner hemispherical concave surfaces eter and then by properly controlling the placing and the dimensions of .plug 75 and bores 74 and 73. In one specific example, the outside diameter of core 38 is made in the order of 7.5 inches. Since the standard diameter of the finished ball is 8.594 inches, the thickness of cover in the above example becomes equal to .547 inch. The thickness of wall 67 is not critical and is a function 'of the physical properties of the synthetic resin used for making thecover. It is also a function of the physical properties of the inner core 38 in that the final prop erties of the core and the final properties of the cover should match each other as closely as possible in terms of their respective elasticities so that the two could function as a unit. When this is the case, the thickness of the cover can be reduced to a very large extent and made axis of the ball which passes through its center of gravity and through the high density weight block 26. This is accomplished as follows; the ball, after it 'has been turned down in a lathe, is placed in a mercury bath, the bath having the shape of a concave hemisphere of greater diameter than the diameter of the ball, and the ball places itself at once so that the above axis finds itself in the vertical position. A centering punch is aligned with the vertical position which corresponds to the axis of symmetry of the bath. The punch forms a sliding engagement with the bowl. The punch is struck with a hammer and its cone-shaped sharp top makes a center-punch impression in the ball at the point of the location of the vertical axis passing through the geometric center of the ball and the center of gravity. The center punch mark is then used for properly positioning plug 75 and bores 74 and 73 in concentric relationship with the above axis.

' mark all required data, such as the weight, the nameof 38. Bore 74 is used for inserting a synthetic resin plug 75 which can have a different color than the color'of the outer lining 67. Plug 75 is provided, ifso desired, with suitable shoulders 76 and '88. In practice it has been found that such shoulders are not necessary and, therefore, plug 75 is a straight cylinder of 'any suitable diamete'nand its length is made sufficiently long, so as to make it protrude some fraction of an inch beyond the outer surface of the outer lining, or cover, 67 of the ball. Plug 75 is a partially or a completely cured plug made eitherof the same or compatible resin with respect to theresinusedfor making the outer cover, 67 so that positive adhesion and bonding takes place between the plug and cover 67. Plug 75 is cured prior to the curing of cover 67 so that it could be machined to the pro'per outer diameter and, also, so that it can act as a laterial support, or a supporting shaft, for core 38 together with mandrel 68, the two holdingcore 38 in a'concentric relation with respect to mold 53. J It should be noted here that such concentric relationship is obtained, and the uni-' formity of the thickness of the outer cover 67, is insured by the prior turning of core 38 on a lathe to the desired diamthe maker,trademark, etc.

Before proceeding with the further discussion of mold 53, it should be noted here that cavities 56 and 57 are 'used alternately, first for heating the mold, with steam as a heating medium, during the curing process, and then, upon the completion of the curing process, for cooling the same mold with water.

The mold is also provided with suitable means for holding the two halves 54 and 55 of the mold in a clamped position with respect to each other, such as plates 78 and 79 andbolts 80 and 81. The upper half 54 of the mold is provided with a bore 82 and the lower half 55 of the mold is provided with a bore 83. Bore 83 is connected to pipe 52 which is connected to the piston-cylinder combination 51-50 used for injecting the resinous mixture 84 into the spherical gap between core 38 and the walls 58 and 59 of the mold. High pressure is exerted on piston 51, and resin 84 is then injected into the mold through pipe 52 and bore 83. Bore 82, in the upper half 54 of the mold, is connected to a pipe 85 which connects bore 82 to a sight gauge 86 and then through the pipe 87 to a vacuum pump 88.

The operation of the mold illustrated in FIGS. 4 and 5 is as follows:

After a fully cured core 38 has been removed from mold 12-1211, and after this core has been imparted a true spherical shape in a lathe or a grinder, marked in the mercury bath, and recesses 74 and 73 are drilled at opposite poles, plug 75 is inserted into recess 74 and mandrel 68 is inserted into recess 73. The ball is then mounted on top of the lower part 55 of the mold. Core 38 then is in concentric position with respect to the lower 1 mately 30 minutes;

of placing the upper half 54 of the mold on top of the lower part and clamping the two together by means of. The mold is then connected to vacuum bolts 80 and 81. pump 88 by opening valves 89 and 90. A manometer 91 is also connected to line 87 for indicating the degreeof vacuum obtained through the entire transfer. system. After proper vacuum has been reached, valve 92 is opened and resin 84 is injected into the mold by applying pressure to piston 51' whereupon .resin 84 is transferred from cylinder 50 into the mold through pipe 52... The injection process is continued until resin 84 also appears in the sight gauge 86 whichindicates that mold 53 has been properly filled with resin. Mandrel 68 is withdrawn from its position illustrated in FIG. to the extent that its tip is flush with surfaces 60 and 61 of the mold after the mold has been filled'with resin. Since the resin. at this instant. is at a relatively high pressure, the void formed bythe withdrawal of mandrel 68 is immediately filled piston '51 is disconnected from the source of pressure, and

with resin." At this stage, valves 89 and 92 are closed,

circulatedthroughcavities 56 and 67 and steam ducts 9 1,

92, 93, and 94 illustrated in FIG. 4.v v

The curing process is carried out at the temperature apropos to the resin, 'hardener, flexibilizer, diluent, etc., present in-the formulation. Hardness of the finished cover is .not a direct function of the temperature butof the composition. Those skilled in the art readily know the correct temperature and time necessary to produce. a

proper cure in an epoxy formulation. For example, the formulation of the for'egoi'ngExample III was cured at about 300. F. for about 15 minutes.

After the curing period, the mold is cooled by circulating water throughthe mold for aperiod' of approximately ten. minutes and the mold then is allowed to cool'for an additional. thirty minutes, whereupon the mold is opened and the ball is removed from the mold. After the removal of the ball fro'mthe mold, it is further cooled by with a concave hemispherical portion 605 of the die. In order to facilitate the introduction of the powder material into the lower die-member 602,- this-member is also pro- -vided with a slanting surface 606 which acts as a funnel for the rawmaterials. 1

The matching member of the die assembly includes a hemispherical concave portion v607, a cylindrical member 608, or a piston 608, which is provided with a fiat surface, or flange, or shoulder, 609, two slanting surfaces 610-and 611, and a ring-shaped surface 612 which interconnectsthe slanting surfaces 610 and 611. This die member, is also preheated to 310 F. by using the circulatingsteam'. I

After aproper amount of raw; materials has been introduced into the-lower die member 602, the. upper die member 608 is lowered intothe converging portion 606-601 of the die with'the result that the raw materials become compressed between the two dies, practically all of the materialgoingintot-he two hemispherical concave portions 607 ,and605 of the die members, and only a small amount being squeezed out sidewise, as is the case in pressure molding. A pressure .of 10,000 pounds per square inch is used for compressing the flour. In order to obtain the desired density of the material, .a compression ratio of approximately 4. to 1 isused, and this compression ratio can also be varied for obtaining the balls immersing it in-water atroomtemperature for .approxi- After the ball 'is removed from the mold, and com pletely cooled, it is turned to its proper size in a lathe or a grinder and then subjected to a fine grind; engraving, buffing with wax, and the final polish.

Referring now toFIG. 6, it illustrates the method of making the core from chipped pieces vof wood, or sawdust, or wood flour, or wood shavings, which are mixed withsuch synthetic resin glues as phenol formaldehyde, epoxy resins, polyester resins, melamine, urea formaldehyde,etc.

In order to produce a suitable core made of wood flour,-

the following proportions of wood fiour, asbestos fiber and'resin were found to produce a core capable of withstanding very severe impacts and have proper hardness, elasticity and density so as to produce a sixteen-poundball with an epoxy resin cover.

(1)Wood flour (70 'meshDouglas fir), parts weight.

(2) Asbestos fibers, 20 parts by weight. .(3 Phenol formaldehyde, 20 parts by weight. I In the above composition, phenol formaldehyde may be replaced with an epoxy resin compounded with urea and melamine. The resins should be in a powdered form, rather. than liquid, for proper mixing and subsequent handling of the mixture in the molds.

Inmaking the cores, the ingredients,which are all in a powder form, are thoroughly intermixed prior to their introductioninto the molds, or dies, illustrated in FIG. 6, and then preheated to a temperature of 150 F. The mold is also preheated to a temperature of 310 F. by circulating steam through the jackets of' the mold.- I The preheated mixture is then dumped into a slightly convergent cylinder 601 in a stationary die member 602' which terminates in a slanted surface 603 and a horizontal surface 604, the latter interconnecting the cylinder .ing steam.

such as three to'eight hours.

Suchpartial. curing extends the' curing reactions approximately through one inch of the outer crust. Accordingly, in order to obtain complete curing of the ball through its entire body, post curing is required and such post curing may ex tend over a period of many hours, Post curing for three hours at 170 F. produces-satisfactory post curing when the core is made of wood flour and phenol formaldehyde resin. The post curing is conducted inany suitable autoclave after the ball'core is removed fromthemold.

Accordingly, the partial curing that is conducted while the material is heldin the compressed state by the two molds, is reducedwto the irreducible minimum which is necessary in order to obtain a reasonably stro ng ball upon the conclusion of this preliminary. curing, or a ball which can be handled quite safely while it is being taken out of the 'mold, put into an autoclave, etc. Moreover, it is also, necessary as have at this stage that amount of preliminary curingwhich-will enable the outer cured crust to hold together in the fullycompressed state the uncured central portion of the material without bursting of the ball or undue warp-age or expansion. in diameter of the ball." All of the above is accomplishedwith the twenty minute curing time-within the mold.

Other modes of applying theprinciple of the invention may be: employed, provided the features stated in any of the following claims or the"equivale'nt of such be We, therefore, particularly point out and distinctly claim as our invention: w

1. A bowling ball of spherical shape comprising a co're and a hard, molded and-cured epoxy resin cover in adhesive relationship tosaid core. I

2. A b'owlingball of spherical shape comprising a core having at least the outer surface of hard rubberand a surrounding coverof cured-and hardened epoxy resin in direct, firmly adhesive contact with saidrubber.

- 400 prior to curing.

4. A bowling ball of claim 2 in which said core includes a center portion of compressed wood particles, and an outer layer of hard rubber.

5. A bowling ball of spherical shape comprising a core having at least the outer surface of fully cured hard rubber and a surrounding cover of cured and hardened epoxy resin in direct firmly adhesive contact with said rubber.

6. The bowling ball of claim 1 in which said core is of molded wood.

7. The bowling ball of claim 1 in which said core is of molded wood including wood flour, asbestos fiber and a resinous binder.

8. A bowling ball of spherical shape having a molded hard rubber core and an epoxy-resin cover applied over said core.

9. A bowling ball of spherical shape having a molded composite hard rubber and cork inner core, an intermediate hard rubber shell, and an epoxy-resin cover applied over said intermediate shell.

10. A bowling ball of spherical shape-comprisingat least one core and an epoxy-resin cover contiguous there with and completely enveloping said core, said epoxyresin prior to curing, having an epoxide equivalent weight of from about 170 to about400;

11. A bowling ball of spherical shape comprising a molded wood core and a cured epoxy-resin cover contiguous thereto and in adhesive relationship therewith and completely enveloping said core, said epoxy-resin prior to curing. having an epoxide equivalent weight of from about 170 to about 400, and said core consisting essentially of finely divided wood, inorganic fibers and a resinous binder.

, lent weight of from about 170 to about 400, from about 2 to about 20 parts per hundred parts of resin of a standard reactive diluent, fr om about 5 to about 70 parts per hundred parts of resin of filler, fromabout 3 to about 100 parts per hundred parts of an epoxy curing agent, from about 0 to about 100 parts per hundred parts of resin of a fiexibilizerand .from about 0 to about 20 I parts per hundred parts of resin of pigment.

13. The bowling ball of claim 12 having a molded and cured core consisting, prior to curing, essentially of finely divided wood, inorganic fiber and a resinous binder.

14. The bowling ball of claim 12 have a molded cured core consisting essentially of hard rubben.

15. The bowling ball of claim 12, having a molded cured core consisting essentially of hard rubber and cork.

References Cited by the Examiner UNITED STATES PATENTS 573,797 12/96 Rockwell 273-82 575,128 1/97 Rockwell 273-63 1,504,461 8/24 Whelan 273-63 1,518,130 12/24 Barach 27363 1,620,310 3/27 Whelan 273-82 2,166,950 7/39 German'et al. 2,291,738 8/42 Luth et al. 273-63 2,362,269 11/44 Hall 273-63 2,414,672 1/47 Sauer 273-63 2,528,934 11/50 Wiles 273 2,684,504 7/54 Sell 1859 2,814,835 12/57 Faulkner 1859 2,839,301 6/58 Hunter 27363 2,856,679 10/58 Burkhardt.

2,944,821 7/60 Mason.

12. A bowling ball of spherical shape comprising at least one core and a cured epoxy-resin cover contiguous therewith and completely enveloping said core, said epoxy-resin cover consisting essentially of the cured reaction product of an epoxy resin having an epoxide equivav OTHER REFERENCES Modern Plastics for October 1952; pages 89-94 cited.

RICHARD C. PINKHAM, Primary Examiner.

ELLlS E. FULLER, LEONARD W. VARNER, 111.,

Examiners. 

1. A BOWLING BALL OF SPERICAL SHAPE COMPRISING A CORE AND A HARD, MOLDED AND CURED EPOXY RESIN COVER IN ADHESIVE RELATIONSHIP TO SAID CORE. 